According to a conventional liquid pressure-feed device disclosed in Japanese Patent Publication No. Sho 48 (1973)-27648, a working fluid inlet port, a working fluid discharge port, a liquid inlet port and a liquid discharge port are formed in a closed vessel, and an intake valve body for opening and closing an intake valve port of the working fluid inlet port and an exhaust valve body for opening and closing an exhaust valve port of the working fluid discharge port are switched over between opening and closing in accordance with the level of liquid accumulated within the closed vessel. First, the exhaust valve port is opened and the intake valve port is closed, allowing liquid to flow into the closed vessel from the liquid inlet port and then the exhaust valve port is closed and the intake valve port is opened to feed the liquid accumulated in the closed vessel from the liquid discharge port under pressure. In this conventional pressure-feed device, an inlet-side check valve port of the liquid inlet port is formed in the closed vessel, an inlet-side check valve body for opening the inlet-side check valve port toward the interior of the closed vessel is disposed within the same vessel, a closed vessel outer opening for opening the working fluid discharge port outwards of the closed vessel is formed, and the working fluid discharge port is connected to a liquid generation source side through an outer pipe connected to the closed vessel outer opening. According to a liquid pressure-feed device disclosed in Japanese Patent Laid-Open Publication No. 2005-325775, a working fluid inlet port, a working fluid discharge port, a liquid inlet port and a liquid discharge port are formed in a closed vessel, and an intake valve body for opening and closing an intake valve port of the working fluid inlet port and an exhaust valve body for opening and closing an exhaust valve port of the working fluid discharge port are switched over between opening and closing in accordance with the level of liquid accumulated within the closed vessel. First, the exhaust valve port is opened and the intake valve port is closed, allowing liquid to flow into the closed vessel from the liquid inlet port and then the exhaust valve port is closed and the intake valve port is opened to feed the liquid accumulated within the closed vessel from the liquid discharge port under pressure. In this conventional liquid pressure-feed device, an inlet-side check valve port of the fluid inlet port is formed within the closed vessel, an inlet-side check valve body for opening the inlet-side check valve port inwards of the closed vessel is disposed within the same vessel, and a communication passage for connecting the working fluid discharge port to the liquid inlet port is formed in the closed vessel.
The former conventional liquid pressure-feed device referred to above has involved a problem that the working fluid discharge port cannot be connected to the liquid inlet port of the closed vessel without going through an external pipe. The latter conventional liquid pressure-feed device has involved a problem that the working fluid discharge port cannot be connected to the liquid generation source side through an external pipe.